Hydroprocessing can include processes which convert hydrocarbons in the presence of hydroprocessing catalyst and hydrogen to more valuable products.
Hydrocracking is a hydroprocessing process in which hydrocarbons crack in the presence of hydrogen and hydrocracking catalyst to lower molecular weight hydrocarbons. Depending on the desired output, a hydrocracking unit may contain one or more beds of the same or different catalyst. Hydrotreating is a hydroprocessing process used to remove heteroatoms such as sulfur and nitrogen from hydrocarbon streams to meet fuel specifications and to saturate olefinic compounds. Slurry hydrocracking is a slurried catalytic process used to crack residue feeds to gas oils and fuels.
Hydroprocessing recovery units typically include a stripper for stripping hydroprocessed effluent with a stripping medium such as steam to remove unwanted hydrogen sulfide. The stripped effluent then is heated in a fired heater to fractionation temperature before entering a product fractionation column to recover products such as naphtha, kerosene and diesel.
Maximizing diesel production is desired in several regions of the world due to its increasing demand as a motor fuel. Hydrocracking units are most effective in producing diesel. The common way to increase diesel production is to add kerosene to diesel but kerosene is the primary component for jet fuel which is a highly profitable fuel. Thus, increasing diesel production in the conventional way is at the expense of reducing jet fuel, so there is little to no monetary advantage for moving the kerosene cut into the diesel cut. Moreover, only so much heavy naphtha can be moved into the kerosene cut without diminishing jet fuel performance.
There is a continuing need, therefore, for improved methods of recovering fuel products from hydroprocessed effluents and for increasing diesel recovery.